What Are Pesticides?
Pesticides are chemicals that deter and eliminate certain pest populations including insects, rodents, fungi, weeds, and other animals. The agricultural industry relies heavily on the application of pesticides to protect crop yields from damage. They are also commonly used to exterminate mosquitoes to prevent the spread of malaria, West Nile virus, and yellow fever. Pesticides are known by various names, depending on their target. These include insecticide, fungicide, and herbicide (to name a few). This article takes a closer look at the environmental impact of pesticide use.
What Is the Environmental Impact Of Pesticides?
Because pesticides are sprayed over large areas of land, they have a widespread impact on the environment. Research has shown, for example, that over 95% of herbicides and over 98% of insecticides do not reach the targeted pest. This is because pesticides are applied over large tracts of land and carried away by wind and water runoff. As these chemicals travel to other areas, they affect a number of plant and animal species. Additionally, storage, transportation, and production allow some quantities of pesticides to be introduced to the environment.
While research concerning the exact impact of pesticides on the environment is varied, it has increased over the last few decades. As a result of some of this research, both the United States and the European Union have stopped using organophosphate and carbamate insecticides, some of the most toxic of all pesticides. Companies have begun developing pesticides with reduced side effects for non-target species as well.
Impact Of Pesticides On Soil
Once applied to crops, pesticides work their way into the soil, where it has devastating effects. Perhaps the most detrimental of these effects is that pesticide causes biodiversity loss in soil. This means the soil has a lower quality overall and is less fertile. Additionally, it removes a large percentage of organic matter. Organic matter helps soil retain water, which can be extremely helpful to agricultural workers, particularly during droughts. This lack of organic matter also allows pesticides to continue to build up in the soil instead of breaking down the chemicals. Less fertile soils mean less plant growth, which, in turn, means farmers must use increased quantities of fertilizer for successful crop yields.
Impact Of Pesticides On Water
Pesticides seep into the soil and find their way into groundwater. Additionally, they may be washed into nearby streams and rivers. In fact, research has found that every stream and around 90% of all water wells are polluted with pesticides in the US. Rain and groundwater sources have also been found to be contaminated. Several countries around the world, including the US and the UK, have passed drinking water safety laws in an attempt to regulate and reduce the amount of pesticides found in public water systems.
Impact Of Pesticides On Air
Pesticides do not only collect on plants, seep into the ground, and wash away into nearby waterways. These chemicals are also easily carried on the wind to other, non-agricultural areas, in a phenomenon known as pesticide drift. Pesticide drift occurs when pesticide is sprayed on crops and carried off by the wind before reaching the plants or when it undergoes volatilization. Herbicide (or pesticide) volatilization is what happens when the chemical reaches its intended destination and later evaporates into the air, being carried downwind. It is more common in warmer climates and seasons when evaporation occurs at a faster rate, preventing the pesticide from being absorbed into the ground.
Once the chemicals leave the intended target, they can be carried across long distances, potentially entering delicate ecosystems. The distance that these pesticides can travel depends on wind speed, relative humidity levels, and external temperatures. This means that warmer summer temperatures typically result in increased pesticide concentrations in the air, which are then introduced to human and animal respiratory systems. Some pesticides also emit volatile organic compounds that react with other chemicals in the atmosphere and create tropospheric ozone, a greenhouse gas that affects how long methane and other hydrocarbons remain in the atmosphere. In order to prevent pesticides from being carried through the air, many countries have implemented regulations that require windbreaks or buffer zones around targeted crops. These can take the form of tall pine trees planted around the agricultural land or empty fields surrounding the pesticide-treated area.
Impact Of Pesticides On Wildlife
Pesticide use affects both plants and animals. Chemicals reduce nitrogen fixation, the symbiotic relationship between nitrogen fixing bacteria and plants that is required for proper plant growth. A reduction in nitrogen fixation results in reduced crop yield, particularly in legume type plants. When this occurs, additional fertilizer must be applied to the fields. Pesticide use is also directly linked to the constantly declining bee population, a species which is vital to plant pollination. In fact, researchers have studied this effect, known as pollinator decline, in order to understand Colony Collapse Disorder. This disorder occurs when bee colonies are exterminated without prior indicators of population decline. The US Department of Agriculture has released an estimate suggesting that US farmers lose approximately $200 million annually due to reduced pollination.
Wildlife other than plants and bees are affected by pesticide use as well. Many animal species may inadvertently ingest pesticides after eating food that has come into contact with the chemicals. Humans also have this risk. Because of its ability to be carried over long distances, these chemicals may also reach other ecosystems and cause significant damage. Pesticides have been linked to reduced plant growth in non-target areas, which leaves wildlife with little to no food source. These animals are then forced to leave their territory in search of sustenance or die due to a lack of available food. Additionally, pesticides are carried up the food chain when animals consume pesticide-contaminated foods. This was seen in North America with birds of prey, particularly eagles. These birds were consuming pesticide-contaminated fish. The pesticide underwent bioaccumulation and was passed on in a more concentrated form to the hatchlings of these birds, causing them to die at a young age or while still incubating in the egg.
Plants, birds, fish, reptiles, amphibians, and mammals (including humans) have all been affected by pesticide use. It appears that this man-made chemical was invented with the intention of improving and increasing crop yields to ensure continued health of the human population. Unfortunately, its use has come with unintended and fatal consequences. Governments around the world need to act in order to control pesticide application and prevent some of its harmful and increasingly common side effects.
About the Author
Amber is a freelance writer, English as a foreign language teacher, and Spanish-English translator. She lives with her husband and 3 cats.
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